<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // String()
        var cat=String(123);
        console.log(cat);
        // toString()
        var dog=123;
        var a=dog.toString();
        console.log(a);
        // 加号
        var mouse=123;
        var c=mouse+"";
        console.log(c);

        var test=false;
        var text= test.toString();
        console.log(text);
    </script>
</body>
</html>